High capillarity bristle



Oct. 1, 1946. E; H. HAUX HIGH CAPILLARITY BRISTLE Filed June-1. 1944 INVENTOR. E'AMEE'H HAWX Patented Oct. 1, 1946 UNITED STATES PATENT OFFICE V 2,4(l8, 'l18 l HIGH CAPILLARITY BRISTLE 1 Elmer H. Ilaux, Baltimore, Md., assignor to Pittsburgh Plate Glass Company, Allegheny County, Pa., a corporation of Pennsylvania 7 Application unel, 1944, Serial-No. 538,277

7 Claims. 1

The present invention relates to bristles for use in the manufacture of brushes such as are employed as means for applying paints, varnishes and the like to surfaces which are to be coated, and it has particular relation to the preparation of bristles of the foregoing type from a synthetic plastic material.

One object'ofthe inventionis to provide a synthetic bristle which is adapted to retain paints,

varnishes and such like liquids without undue tendency to run or spatter when a brush embodying the bristles is dipped into the liquids.

A second object of the invention is to provide a simple and convenient method of forming such bristles.

These and other objects of the invention will be apparent from consideration of the following specification and the appended claims.

Heretofore, in the manufacture of such brushes as are employed in painting or other coating operations, hairs or bristles of animals have been employed in order to form a brush element. The better grades of bristles have been obtained from geographical regions wich are now largely inaccessible-owing to war conditions. In order to supply the need of bristles, it has therefore been proposed to spin monofilaments from a synthetic plastic material and then to cut the filaments into suitable lengths for bristles. The synthetic bristles, as heretofore obtained, do not entirely duplicate the characteristics of the animal bristles because the latter usually are more orles frayed at the tips, and also the surfaces thereof usually are coated with or formed of overlapping scales. These features are highly desirable inasmuch as they increase capillarity and thus greatly assist in retaining or holding the paint or other liquid into which a brush embodying the bristles may be dipped. Accordingly, brushes embodying a good grade of natural bristles are relatively free from tendency of the liquids in the brush to spatter and to run back down the handle when the brush is tipped upwardly. Of course, the synthetic bristles inherently are quite smooth and in many instances, do not readily retain paint In order to improve the paint-retaining charprovide a roughened paint-retaining surface in the product.

provide bristle lengths; and

acteristics of synthetic bristles, it has heretofore been proposed to subject them either before or after introduction into a brush, to a buffing action by means of an abrasive body, such as a conventional grinding wheel, driven at relatively high speed. This operation, of course, is relatively expensive.

In order to provide inexpensively synthetic bristles having high capillarity and good paint retaining characteristics, it is now proposed to incorporate into the stock from which the synthetic bristles are spun, a filler material preferably of a fibrous or porous nature designed to portions Fig. 4 is an elevational View of one of the bristles embodying the invention.

In the drawing, like numerals refer to like parts throughout. I

A bristle 8 as shown in Fig. 4, embodying the principles of the present invention, preferably is substantially tapered from butt to tip, which effect conveniently can be obtained by spinning a solution of synthetic plastic containing a fibrous or porous filler material by means of the apparatus shown in Fig. 2. In accordancewith this showing, a solution of plastic and filler is supplied through a conduit l0 from any convenient source to a pumping mechanism H. Preferably, the latter is of the type illustrated in the applications of John J. Gregory, Serial Nos. 459,251,

PatentNo. 2,374,744, patented May 1, 1945, and '459,252,'filedseptember 22, 1942. This mechanism' is designed to deliver the solution through a conduit IE to a spinner head l3 disposed in a "coagulating bath [4 containing a liquid agent adapted to set the fluid plastic. It is to be unvided' with a suitable plate having spinnert openings formed therein through which the monofilaments I5 aredrawn out into the setting bath. Byreason of the pulsating pressure generatedby pump II, the filaments as shown in Fig. 3 have alternating thickened portions 1 6 and constricted I1 corresponding respectively to the butts and tips of the bristles when the filaments are cut up into sections of bristle lengths.

The filaments after they have been'set in the bath, are collected into a cable or bunch l5a about pulley I1 and are then drawn upwardly and about a series of take-up pulleys 18 which conveniently may 'be'driven at a constant speed in,

order to maintain a desired degree of tension upon the filaments in the setting bath, The

evaporated.

The dried filaments are delivered from chamber is to a suitable drum 2!! designed to maintain a predetermined delivery rate of the filaments. 'This drum may also be associated with a convenient cutting mechanism designed to cut the filaments through their thickened portion's.

thus providing bunches comprising units each of which includes two bristle lengths. A suitable cutting apparatus is shown in the John J. Gregory application Serial No. 499,264 (Patent No. 2,356,841, patented August 29, 1944), filed August 19, 1943. Subsequently, the bunches are cut into single bristle lengths and are then'ready for transmission to the brush maker.

Various types of plastic may be employed for spinning .the synthetic bristles in accordance with the provisions of the present invention, Apparatus, as shown, is designed for spinning monofilaments suitable for use as bristle stock from solutions of plastic such as cellulose diacetate, cellulose triacetate, cellulose acetobutyrate, or the like. In this operation, the solution of plastic is simply admixed with the desired filler in appropriate amount prior to delivery to the spinning apparatus. inert and it be of a fibrous or at least a porous nature. Wood flour is particularly satisfactory for the purpose, but maybe replaced by ground asbestos, cotton flock, sisal or the like. Silica gel in powdered form or diato-maceous earth, bone char in powdered form might be employed as embodiment of a porous, absorbent material. The filler must be sufiiciently finely round to pass through the spinnerets without any undue tendency to clog the latter, approximately 200 mesh material seems to be satisfactory, but other sizes, so long as the spinnerets do not clog or the material become so fine as to lose its capacity to induce high capillarity in the surface of the filaments, may b employed. The proportion of filler material employed may vary over a relatively broad range, but preferably should be approximately Within the limits of l to 50 percent based upon the solids content of the plastic composition. These seem to be approximately the extreme rang-es and in most cases a composition of intermediate filler content is to be preferredfor example, to 40 percent.

The following is illustrative of a composition which may be employed in forming bristle stock in accordance with the provisions of the present invention:

Parts Cellulose triacetate 150 Wood flour 50 Tetrachlorethane 720 Methyl alcohol 160 employed as a setting bath in container Hi. It is to be understood that cellulose triacetate can be substituted by cellulose diacetate which when spun provides filaments of higher tensile strength than the triacetate. Similarly, cellulose triacetate can be replaced by cellulose acetobutyrate.

It is to be understood that monofilaments of nylon, the resinous polymer of a dibasic acid It is desirable that the filler be I and a diamine, polymerized vinylidene chloride or polymerized vinyl chloride may be employed in place of the cellulose esters. These latter are relatively insoluble but fusible materials which are best spun into filaments by fusing them down into fluid state prior to the spinning operation. The filaments set into solid state upon cooling. Of course, the fibrous or porous filler is incorporated into the plastic prior to a spinning operation and may be in a ratio of 1 to percent as above described. Central filamentary cores of nylon, polymerized vinylidene chloride or the like can, also, be drawn through the spinnerets to receive coatings of a solution of cellulose triacetate or other soluble plastic and a fine fibrous filler. The coated filaments can then be cut into bristle lengths.

The formation of the bristles into brushes, after they have been cut from the spun filaments, follows conventional procedure. For example, .the bristles are merely inserted in a ferrule 33 and the spacer bars 3i. are inserted in the body portions by well-known technique. Subsequently, the butts are dipped'in-to rubber or other adhesive material in liquid state and subjected to a cure in order to bond the brush. The brush is secured in place in the ferrule by means of nails 39 which may conveniently be driven through the metal constituting the ferrule. The brush is completed by inserting a handle li and securing it in place by means of nails 42.

The bristles embodying the present invention have a high degree of capillarity and readily hold an ample supply of paint or other coating material and the brush, when so charged, will withstand the usual brushing operations without any undue tendency of the paint to run or spatter.

I is to be understood that the forms of the invention herein disclosed are to be considered merely exemplary. Numerous modifications may be made therein without departure from the spirit of the invention and the scope of the fol lowing claims.

What I claim is:

1. Abrush comprising tapered synthetic bristles of plastic having surfaces roughened by means of a comminuted fibrous filler embedded in the plastic.

2. A brush comprising tapered bristles of nylon containing a finely-divided fibrous filler imparting roughness to the bristles.

3. A paint brush comprising tapered bristles of plastic containing 1 to 50 percent of a finelydivided fibrous filler imparting roughened sur faces of high capillarity to the bristles.

4. A paint brush comprising tapered synthetic bristles of plastic containing 1 to 50 percent of wood flour.

5. A brush comprising tapered synthetic bristles of cellulose diacetate containing a finely-divided fibrous filler adapted to impart high capillarity to the bristles.

6. A brush comprising tapered synthetic bristles of cellulose acetobutyrate containing 1 to 50 percent of an inert fibrous filler imparting high capillarity to the surface of the bristles.

'7. A bristle suitable for brushes and being tapered from butt to tip and being formed of plastic containing a plastic and l to 59 percent of an inert fibrous filler imparting high capillarity to the bristle.

ELMER H. HAUX. 

